I'd buy one of those "CD laser lens cleaner" discs. They only cost $10-15. If that doesn't help, then it's probably time to get a new one. Unless you want to take the top off and try to clean the lens yourself...worst case is you mess it up and have to replace it anyway.
I saw some links estimating the effective life of a laser unit at 10,000 hours playing time. So if the player is more than 10 years old, there's a good chance the laser is dying.
The laser unit of my Marantz SACD player started malfunctioning after 17 years. Replacements hard to find and you need a competent technician. A costly procedure. New players are one grand or more.